Postal scales are well known in the art as are portable weighing scales which can be moved from place to place or left on a counter or other surface at a particular location. These postage scales are typically equipped with means of weighing packages including letters and parcels, and capable of combining the weight and the shipping rate information stored therein to determine the postage and other charges for shipment of the packages.
Many of the scales are also equipped with means of displaying the weight of a package, along with the postage and other shipping charges during the weighing process. For aesthetic reasons, the display screens of such scales are compact and relatively small. As such, the amount of information displayed on one such screen is extremely limited. Moreover, in use, when a large package is weighed, the display and keypad may be visually blocked and inaccessible if the package has a dimension larger in size than the position of the display and keypad. Such displays are typically fixed and non-adjustable. Such displays also present problems when, for example, there is insufficient light or when there is a glare present on the display screen due to overhead lights or sunlight. In addition, for those fixed displays which employ liquid crystal display (LCD) technology, they normally afford an extremely limited viewing angular range, outside which the display contrast deteriorates substantially. Since a user cannot adjust a fixed display to improve the lighting condition or to increase the viewing range, the user under these unfavorable conditions tends to be inefficient and susceptible to eye strain.
U.S. Pat. No. 4,979,579 discloses a portable weighing device, namely an electronic balance, in which the horizontal display pivots about the weighing area and telescopes merely to adapt to the contour of the weighing area. However, the display is not longitudinally extendable so as to be able to be viewed from above irrespective of the size of the package placed on the scale.
Other scales are known in the art, including U.S. Pat. Nos. 6,043,438, 6,013,878, 5,203,419, 4,979,579, 4,632,199, 3,838,744, 2,805,055, and D358590. All patents listed herein are incorporated herein by reference in their entirety.
Thus, none of the prior art portable scales known to applicant is capable of providing a compact postal type scale of unitary design capable of weighing a plurality of different size or dimension packages in which the display and keypad (input and output unit) are selectively extendable from the scale so as to be visible and accessible no matter what the size of the package placed on the scale throughout a given size range, while also being retractable into a compact unitary rest position with the scale for normal size packages. These disadvantages of the prior art are overcome by the present invention.